Need to break vacum in water softener drain line

have a 1/2" pex drain line running outside as I can't run it into my septic system anymore.......I installed a Watts N36 vacuum breaker at the highest point to allow all the water to drain and eliminate any freezing problems. During regeneration the valve disk flutters making a moaning/groaning sound. Any ideas? Drain is under house pressure when it runs....

The 1/2" PEX has a smaller ID than 1/2" PE drain line so you are reducing flow to drain and that is not a good idea because the gpm flow rate is already flow controlled in the control valve. Most residential softners require a 1/2" ID drain as a minimum. If you have to or want to use PEX, use 3/4".

How long is the run of pex? Where along the run is this vacuum breaker? Change out the rest of the run after the vacuum breaker to larger pipe provided you can have enough standpipe to assure it cannot backup and overflow. An AAV on the bigger drain pipe should be quieter.

6' from the softener to the vacuum break which is along the ceiling so make it a 3' rise.....then it runs downhill to a dry well outside of the house less than 30 feet......the drain hose from the softener is 1/2" matchs the pex........the vacuum breaker is attached via a tee with 3/4 pex. connection running vertically

A response to another similar question about drains freezing from water held by a vacuum lock stated that if the end of the drain line is open then the water should drain back to the highest point in the drain line which is in my floor joists.......so my vacuum breaker was actually a waste of money.............does this make sense??

i think I still need a vacuum break as the drain line drips with the leftover water....i tested the other side of the loop to see if the tank valves were leaking and no dripping..so I'm guessing there is still some water left in the drain that is held by a vacuum and is slowly weeping out.....the side that i tested had no vacuum and drained completely. so i'm back looking for some type of vacuum breaker other then the n36 unit i tried....

i think I still need a vacuum break as the drain line drips with the leftover water....i tested the other side of the loop to see if the tank valves were leaking and no dripping..so I'm guessing there is still some water left in the drain that is held by a vacuum and is slowly weeping out.....the side that i tested had no vacuum and drained completely. so i'm back looking for some type of vacuum breaker other then the n36 unit i tried....

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Unless you have a leak, the dripping will quit shortly after regneration.

A response to another similar question about drains freezing from water held by a vacuum lock stated that if the end of the drain line is open then the water should drain back to the highest point in the drain line which is in my floor joists.......so my vacuum breaker was actually a waste of money.............does this make sense??

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With 1/2 pex, the capillary action could trap water unless it was perfectly pitched. A larger pipe such as 1 - 1/2" or 2" PVC properly pitched should drain even without an AAV. Of course, when running buried pipe, ground swelling or settling can create sags or humps that trap water. The larger the pipe the less affected they are by sags or humps.

i tested for leaks at the softeners just to make sure.........i still think that some water is left in the drain near the high point and that's my source of dripping until its gone.........I haven't found too many Vacuum breakers like the watts N36 that might fit................................

before the drain exits the house it has a 15' flat run along the wall........the high point is 3 feet above that.....possible some water left in that..

is there a "breather" available that would add air but not allow the water to leak out...say install it on the top of a tee??

I think I'll use the tee at the highest point of the drain and run the third leg into the washing machine drain as a breather...........if the outside line freezes then it goes into the septic as a backup...voila.....